The invention relates to a drive device with an actuating drive for driving a movable element, in which drive device a lever coupled to the movable element is capable of being driven by the actuating drive via a gear, the lever being acted upon by a firmly supported return spring so as to be capable of being pivoted back into a basic position, and, in the basic position, one lever arm of the lever being acted upon by a stop.
Internal combustion engines of motor vehicles conventionally have a suction pipe, via which fresh air is capable of being supplied to the internal combustion engine. To regulate the quantity of fresh gas to be supplied to the internal combustion engine, the respective suction pipe conventionally has a number of valves, via which the air quantity passing through the suction pipe is capable of being influenced. The suction pipe valves are conventionally activated by an electric motor via a linkage. In this case, for a proper functioning of the internal combustion engine, it is necessary for the suction pipe valves also to be capable of being pivoted in a predetermined way through particularly small angular ranges. Even in the event of a failure of the electric motor driving the suction pipe valves, a return spring in this case ensures that the suction pipe valves are not closed, but are opened in such a way that a defined predetermined power output of the internal combustion engine is reliably ensured. Drive devices of this type for adjusting suction pipe valves of suction pipes of motor vehicles conventionally require a particularly large amount of space, since, in the event of a failure of the servomotor driving the suction pipe valves, excess energy has to be absorbed by the return spring which adjusts the suction pipe valves into a predetermined open position. The high space requirement of these drive devices proves to be a disadvantage, since, for example, electronics have recently needed an increasingly larger space in the engine compartment and only a limited amount of space is available in the engine compartment.
The object on which the invention is based is, therefore, to specify a drive device of the abovementioned type, which requires a particularly small amount of space and which, even in the event of a failure of the actuating drive, reliably ensures an absorption of excess energy of the return spring.
This object is achieved, according to the invention, in that the lever arm is subdivided by a clearance into a first part region and a second part region, the first part region and the second part region each having a free end, and at least the free end of the second part region being deformed in the direction of the free end of the first part region.
The invention proceeds, in this context, from the notion that, in the event of a failure of the actuating drive, excess momentum energy of the return spring may generate a considerable torque peak which should be absorbed in order reliably to avoid mechanical damage to the drive device. Absorption of the momentum energy could be carried out by a swing-out of the components moved in each case. However, for a swing-out of the moved components, it is necessary to have space in the housing of the drive device. This space cannot be provided, since the drive device is intended to be installed in an internal combustion engine of a motor vehicle and therefore is to have a particularly low space requirement. A swing-out of the moved components of the gear of the drive device should therefore not be capable of being implemented via a momentum travel, but by means of components which are present in any case in the drive device. If, then, the actuating drive and the movable element are connected via a separating element, the excess momentum energy can be absorbed by means of this separating element. At the same time, however, it should be reliably ensured that the movable element continues to be capable of being activated in a particularly reliable way. An appropriate uncoupling medium for the separating element is elastic material which is arranged between the actuating drive and the movable element within the drive device. For this purpose, the gear has as separating element an additional lever arm which is designed in its end region approximately in the form of a tuning fork and, by virtue of its resilient action, absorbs excess momentum energy of the return spring when said lever arm is pivoted back by the return spring and comes to bear against the stop.
Advantageously, the free end of the first part region touches the free end of the second part region at at least one free point. By the free end of the first part region coming to bear against the free end of the second part region, the risk of additional deformation of the lever during the operation of the drive device is particularly low. At the same time, when the drive device is in operation, a uniform spring action of the lever is reliably ensured.
Advantageously, the lever has a second lever arm, on which a part toothed ring is arranged, the lever being capable of being driven by the gear via the part toothed ring of the second lever arm of the lever. A drive device can be constructed in a particularly space-saving way via gearwheels or part gearwheels. In this case, it proves sufficient to transmit the rotational movement of the suction pipe valve via a part toothed ring.
Advantageously, the current position of the lever is capable of being detected by a position detection device. In this case, the position detection device may be designed as a potentiometer, but, alternatively, also as a contactless sensor, for example as a magnetoresistive sensor or as a Hall sensor. By means of the position detection device, the in each case current position of the lever and therefore of the suction pipe valve can be additionally detected. As a result, even in the event of a failure of the actuating drive, the current position of the suction pipe valve is capable of being detected reliably.
Advantageously, the movable element is a suction pipe valve of a motor vehicle. A suction pipe valve which is capable of being driven by means of a drive device of this type has a particularly low space requirement and can therefore be arranged in a particularly space-saving way in the internal combustion engine of a motor vehicle.
Advantageously, the movable element is a throttle valve of a throttle valve connection piece, said throttle valve being arranged on a throttle valve shaft. By a drive device of the above-described type being used in a throttle valve connection piece, the latter has a particularly low space requirement and can therefore be arranged in a space-saving way in a motor vehicle.
Advantageously, a throttle valve connection piece with a housing which has a continuous throttle orifice through which a gaseous medium is capable of flowing, a throttle valve fastened pivotably to a throttle valve shaft being arranged in the throttle orifice, comprises, in the housing, a drive device of the abovementioned type. In this case, the throttle valve arranged on the throttle valve shaft is pivotable via the drive device. By virtue of the drive device of the abovementioned type, the throttle valve connection piece has a particularly low space requirement and, moreover, comprises components which have particularly low wear, thus reliably ensuring that the throttle valve connection piece has a particularly long useful life.
The advantages achieved by means of the invention are, in particular, that, on the one hand, the drive device requires a particularly small amount of space, and that, at the same time, even in the event of a sudden switch-off or failure of the actuating drive, the momentum energy of the return spring is capable of being reliably absorbed via the drive device.